A number of times, I have come across the expression "we are (or I am) poorer for it". Today, out of curiosity, I checked a number of dictionaries, but I did not find the said expression listed as an idiom.

May I know whether it is an idiom, or is it some colloquial expression?

I would appreciate it if you could give an example or two to explain its usage.

We are all poorer for his death. (ie, we have all lost something as a result of his death)Today, few people have manners and we are all the poorer for it.If you refuse to go to university, you will be the poorer for it.

In general, the idea is that some event or situation makes us "more poor" than before, not usually in a financial sense but in terms of status, culture, or quality and richness of life.